(1) A person 24 years of age or older who engages in sexual activity with a person 16 or 17 years of age commits a felony of the second degree, punishable as provided in s. 775.082, s. 775.083, or s. 775.084. As used in this section, "sexual activity" means oral, anal, or vaginal penetration by, or union with, the sexual organ of another; however, sexual activity does not include an act done for a bona fide medical purpose.